Analyses for ‘A Translational Paradigm to Study the Effects of Uncontrollable Stress in Humans’
Study 1 Analysis
Laura E. Meine and Katja Schueler
25.06.2020
1 Summary
This script runs analyses on data from study 1. Specifically, it compares data from three groups of participants who underwent escapable stress (EC), yoked inescapable stress (YC), or a control condition (CC), respectively. Here, we use the terms “group” and “condition” interchangeably. Measurements under investigation comprised reaction times (RTs) and ratings under acute stress (stressor aversiveness, control, exhaustion, frustration, helplessness) as well as pre-post changes in affective state (STADI and PANAS questionnaires), effects on working memory (reading span), and escape behaviour (activity, exploration, escapes, efficiency).
2 Sample Descriptives
In total, the sample consisted of N = 80 participants with n = 27 in CC, n = 27 in EC, and n = 26 in YC.
2.1 Age & Sex
3 A Priori Group Difference Checks
3.1 Sex (Chi-square Test)
##
## Pearson's Chi-squared test
##
## data: demo$condition and demo$sex
## X-squared = 0.03256, df = 2, p-value = 0.9839There were no a priori group differences in male-female ratio.
3.2 Age (one-way ANOVA)
Because residuals were not normally distributed, we employed the Kruskal-Wallis test instead of a one-way ANOVA.
##
## Kruskal-Wallis rank sum test
##
## data: age_sess2 by condition
## Kruskal-Wallis chi-squared = 6.518, df = 2, p-value = 0.03843There were some outliers and we checked for the 2 extreme cases but rerunning all analyses without those did not change the results, so we kept them.
3.3 Working Memory IQ (one-way ANOVA)
There were no outliers with respect to working memory IQ.
## Anova Table (Type 3 tests)
##
## Response: workingmem_IQ
## Effect df MSE F pes p.value
## 1 condition 2, 77 140.03 0.81 .02 .45
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '+' 0.1 ' ' 1There were no a priori group differences in working memory IQ.
3.4 Alertness (one-way ANOVA)
There were no outliers with respect to alertness.
## Anova Table (Type 3 tests)
##
## Response: TAPalertness
## Effect df MSE F pes p.value
## 1 condition 2, 77 46.90 1.47 .04 .24
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '+' 0.1 ' ' 1There were no a priori group differences in alertness.
4 Manipulation Check
4.1 Verify Yoking of Stress Durations
##
## Welch Two Sample t-test
##
## data: stress$stress_duration[stress$condition == "EC"] and stress$stress_duration[stress$condition == "YC"]
## t = -0.40496, df = 2111.3, p-value = 0.6855
## alternative hypothesis: true difference in means is not equal to 0
## 95 percent confidence interval:
## -0.06782429 0.04460753
## sample estimates:
## mean of x mean of y
## 6.497424 6.509033There were no differences in stress durations between EC and YC because YC participants were yoked to EC participants. Very slight timing inaccurracies are due to program execution differences. EC and CC performed at ceiling, responding fast enough to each cue as evidenced in mean stress duration well below the 15s maximum in each trial. Thus, there were no group differences in durations.
4.2 Stressor Aversiveness
There were outliers with particularly low aversiveness ratings which we excluded from this analysis because they affected the results. However, since they did not affect subsequent analyses, we included them in those.
##
## Univariate Type III Repeated-Measures ANOVA Assuming Sphericity
##
## Sum Sq num Df Error SS den Df F value Pr(>F)
## (Intercept) 5129.2 1 58.946 38 3306.6313 < 2e-16 ***
## condition 0.1 1 58.946 38 0.0417 0.83921
## sex 4.1 1 58.946 38 2.6383 0.11258
## trial 2.7 3 35.735 114 2.9027 0.03795 *
## condition:trial 0.8 3 35.735 114 0.8176 0.48674
## sex:trial 0.2 3 35.735 114 0.2084 0.89043
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
##
## Mauchly Tests for Sphericity
##
## Test statistic p-value
## trial 0.49209 8.8335e-05
## condition:trial 0.49209 8.8335e-05
## sex:trial 0.49209 8.8335e-05
##
##
## Greenhouse-Geisser and Huynh-Feldt Corrections
## for Departure from Sphericity
##
## GG eps Pr(>F[GG])
## trial 0.66826 0.06084 .
## condition:trial 0.66826 0.44560
## sex:trial 0.66826 0.81288
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## HF eps Pr(>F[HF])
## trial 0.7055209 0.05769324
## condition:trial 0.7055209 0.45119097
## sex:trial 0.7055209 0.82429369## Anova Table (Type 3 tests)
##
## Response: aversive_rating
## Effect df MSE F pes p.value
## 1 condition 1, 38 1.55 0.04 .001 .84
## 2 sex 1, 38 1.55 2.64 .06 .11
## 3 trial 2.00, 76.18 0.47 2.90 + .07 .06
## 4 condition:trial 2.00, 76.18 0.47 0.82 .02 .45
## 5 sex:trial 2.00, 76.18 0.47 0.21 .005 .81
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '+' 0.1 ' ' 1
##
## Sphericity correction method: GG## contrast estimate SE df t.ratio p.value
## X10 - X20 -0.2585 0.134 114 -1.927 0.2261
## X10 - X30 -0.3605 0.134 114 -2.686 0.0499
## X10 - X40 -0.3181 0.134 114 -2.370 0.0973
## X20 - X30 -0.1019 0.134 114 -0.759 1.0000
## X20 - X40 -0.0595 0.134 114 -0.443 1.0000
## X30 - X40 0.0424 0.134 114 0.316 1.0000
##
## Results are averaged over the levels of: condition, sex
## P value adjustment: holm method for 6 tests
Both EC and YC rated the stressor as very aversive (global M = 5.744898). Mean aversiveness ratings did not differ between groups. Stressor aversiveness ratings slightly increased over time. There was no sex effect (at least not if outliers with very low ratings - who happened to be mostly male - were excluded).
4.3 Perceived Stressor Controllability
There were some outliers with respect to perceived control but excluding them did not affect results, so we kept them.
##
## Univariate Type III Repeated-Measures ANOVA Assuming Sphericity
##
## Sum Sq num Df Error SS den Df F value Pr(>F)
## (Intercept) 5577.1 1 751.14 76 564.2915 < 2.2e-16 ***
## condition 507.8 2 751.14 76 25.6912 2.997e-09 ***
## sex 19.3 1 751.14 76 1.9516 0.16648
## trial 6.3 3 160.08 228 2.9718 0.03259 *
## condition:trial 2.1 6 160.08 228 0.4994 0.80852
## sex:trial 0.7 3 160.08 228 0.3391 0.79705
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
##
## Mauchly Tests for Sphericity
##
## Test statistic p-value
## trial 0.35053 1.9017e-15
## condition:trial 0.35053 1.9017e-15
## sex:trial 0.35053 1.9017e-15
##
##
## Greenhouse-Geisser and Huynh-Feldt Corrections
## for Departure from Sphericity
##
## GG eps Pr(>F[GG])
## trial 0.60946 0.05914 .
## condition:trial 0.60946 0.71985
## sex:trial 0.60946 0.69360
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## HF eps Pr(>F[HF])
## trial 0.6237085 0.05786774
## condition:trial 0.6237085 0.72407621
## sex:trial 0.6237085 0.69859412## Anova Table (Type 3 tests)
##
## Response: control_rating
## Effect df MSE F pes p.value
## 1 condition 2, 76 9.88 25.69 *** .40 <.0001
## 2 sex 1, 76 9.88 1.95 .03 .17
## 3 trial 1.83, 138.96 1.15 2.97 + .04 .06
## 4 condition:trial 3.66, 138.96 1.15 0.50 .01 .72
## 5 sex:trial 1.83, 138.96 1.15 0.34 .004 .69
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '+' 0.1 ' ' 1
##
## Sphericity correction method: GG## contrast estimate SE df t.ratio p.value
## CC - EC 1.58 0.428 76 3.701 0.0008
## CC - YC 3.10 0.432 76 7.166 <.0001
## EC - YC 1.51 0.432 76 3.501 0.0008
##
## Results are averaged over the levels of: sex, trial
## P value adjustment: holm method for 3 tests## contrast estimate SE df t.ratio p.value
## X10 - X20 0.2185 0.134 228 1.636 0.4127
## X10 - X30 0.3396 0.134 228 2.542 0.0584
## X10 - X40 0.3505 0.134 228 2.624 0.0556
## X20 - X30 0.1210 0.134 228 0.906 0.9726
## X20 - X40 0.1320 0.134 228 0.988 0.9726
## X30 - X40 0.0109 0.134 228 0.082 0.9726
##
## Results are averaged over the levels of: condition, sex
## P value adjustment: holm method for 6 testsWe observed group differences in perceived control in the expected direction: YC reported lowest, EC middle, CC highest perceived control. There was a trend effect of time and perceived control decreased slightly over time.
5 RTs and Ratings During Stress Exposure
5.1 RTs
There were 2 outliers but only one was excluded from analysis due to exceptionally long RT.
##
## Univariate Type III Repeated-Measures ANOVA Assuming Sphericity
##
## Sum Sq num Df Error SS den Df F value Pr(>F)
## (Intercept) 487033208 1 10884357 72 3221.7238 < 2.2e-16 ***
## condition 1116499 2 10884357 72 3.6928 0.02973 *
## sex 94698 1 10884357 72 0.6264 0.43127
## trial 1170370 39 21891749 2808 3.8492 1.791e-14 ***
## condition:trial 453502 78 21891749 2808 0.7458 0.95296
## sex:trial 261886 39 21891749 2808 0.8613 0.71370
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
##
## Mauchly Tests for Sphericity
##
## Test statistic p-value
## trial 1.0643e-11 1.5261e-45
## condition:trial 1.0643e-11 1.5261e-45
## sex:trial 1.0643e-11 1.5261e-45
##
##
## Greenhouse-Geisser and Huynh-Feldt Corrections
## for Departure from Sphericity
##
## GG eps Pr(>F[GG])
## trial 0.41001 4.583e-07 ***
## condition:trial 0.41001 0.8470
## sex:trial 0.41001 0.6149
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## HF eps Pr(>F[HF])
## trial 0.5334726 1.250428e-08
## condition:trial 0.5334726 8.828213e-01
## sex:trial 0.5334726 6.421118e-01## Anova Table (Type 3 tests)
##
## Response: rt
## Effect df MSE F pes p.value
## 1 condition 2, 72 151171.62 3.69 * .09 .03
## 2 sex 1, 72 151171.62 0.63 .009 .43
## 3 trial 15.99, 1151.31 19014.60 3.85 *** .05 <.0001
## 4 condition:trial 31.98, 1151.31 19014.60 0.75 .02 .85
## 5 sex:trial 15.99, 1151.31 19014.60 0.86 .01 .61
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '+' 0.1 ' ' 1
##
## Sphericity correction method: GG## contrast estimate SE df t.ratio p.value
## CC - EC -30.2 17.1 72 -1.770 0.1618
## CC - YC -46.4 17.4 72 -2.664 0.0286
## EC - YC -16.2 17.4 72 -0.928 0.3566
##
## Results are averaged over the levels of: sex, trial
## P value adjustment: holm method for 3 tests## Call:
## bwtrim(formula = rt ~ condition * trial, id = ID, data = stress)
##
## value df1 df2 p.value
## trial 2.9215 39 214.2123 0.0000
## condition 74.6689 2 465.4222 0.0000
## trial:condition 0.4669 78 278.6381 0.9999## [1] -0.3888654## [1] 1.01121YC was significantly slower than CC but EC and CC did not differ in RTs. Overall RTs showed a steep decrease across the first few trials, then remained fairly constant.
5.2 Exhaustion
There were no outliers with respect to exhaustion ratings.
##
## Univariate Type III Repeated-Measures ANOVA Assuming Sphericity
##
## Sum Sq num Df Error SS den Df F value Pr(>F)
## (Intercept) 4310.7 1 734.92 76 445.7782 < 2.2e-16 ***
## condition 208.5 2 734.92 76 10.7821 7.549e-05 ***
## sex 107.1 1 734.92 76 11.0790 0.001348 **
## trial 6.8 3 107.20 228 4.7871 0.002964 **
## condition:trial 1.4 6 107.20 228 0.5114 0.799439
## sex:trial 2.1 3 107.20 228 1.4547 0.227734
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
##
## Mauchly Tests for Sphericity
##
## Test statistic p-value
## trial 0.48855 2.6448e-10
## condition:trial 0.48855 2.6448e-10
## sex:trial 0.48855 2.6448e-10
##
##
## Greenhouse-Geisser and Huynh-Feldt Corrections
## for Departure from Sphericity
##
## GG eps Pr(>F[GG])
## trial 0.66064 0.009844 **
## condition:trial 0.66064 0.725800
## sex:trial 0.66064 0.236790
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## HF eps Pr(>F[HF])
## trial 0.6782506 0.009244698
## condition:trial 0.6782506 0.730551927
## sex:trial 0.6782506 0.236495798## Anova Table (Type 3 tests)
##
## Response: exhausted_rating
## Effect df MSE F pes p.value
## 1 condition 2, 76 9.67 10.78 *** .22 <.0001
## 2 sex 1, 76 9.67 11.08 ** .13 .001
## 3 trial 1.98, 150.63 0.71 4.79 ** .06 .010
## 4 condition:trial 3.96, 150.63 0.71 0.51 .01 .73
## 5 sex:trial 1.98, 150.63 0.71 1.45 .02 .24
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '+' 0.1 ' ' 1
##
## Sphericity correction method: GG## contrast estimate SE df t.ratio p.value
## CC - EC -1.880 0.423 76 -4.442 0.0001
## CC - YC -1.443 0.427 76 -3.376 0.0023
## EC - YC 0.437 0.427 76 1.023 0.3097
##
## Results are averaged over the levels of: sex, trial
## P value adjustment: holm method for 3 tests## contrast estimate SE df t.ratio p.value
## X10 - X20 -0.1021 0.109 228 -0.934 0.7024
## X10 - X30 -0.3176 0.109 228 -2.905 0.0201
## X10 - X40 -0.3503 0.109 228 -3.205 0.0093
## X20 - X30 -0.2155 0.109 228 -1.971 0.1497
## X20 - X40 -0.2482 0.109 228 -2.271 0.0963
## X30 - X40 -0.0328 0.109 228 -0.300 0.7644
##
## Results are averaged over the levels of: condition, sex
## P value adjustment: holm method for 6 tests
Both stress groups reported sig. greater exhaustion compared to the control group, however, they did not differ sig. from each other. Men in EC reported less exhaustion.
5.3 Frustration
There were a few outliers but none of them were extreme and excluding them did not affect overall results (although it improved statistical significance), so we kept them.
##
## Univariate Type III Repeated-Measures ANOVA Assuming Sphericity
##
## Sum Sq num Df Error SS den Df F value Pr(>F)
## (Intercept) 2782.69 1 649.52 76 325.6006 < 2.2e-16 ***
## condition 180.85 2 649.52 76 10.5805 8.835e-05 ***
## sex 82.07 1 649.52 76 9.6028 0.0027233 **
## trial 11.53 3 134.46 228 6.5195 0.0002999 ***
## condition:trial 10.70 6 134.46 228 3.0225 0.0073098 **
## sex:trial 0.48 3 134.46 228 0.2733 0.8446069
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
##
## Mauchly Tests for Sphericity
##
## Test statistic p-value
## trial 0.73 0.0002693
## condition:trial 0.73 0.0002693
## sex:trial 0.73 0.0002693
##
##
## Greenhouse-Geisser and Huynh-Feldt Corrections
## for Departure from Sphericity
##
## GG eps Pr(>F[GG])
## trial 0.81419 0.0008414 ***
## condition:trial 0.81419 0.0126408 *
## sex:trial 0.81419 0.8037775
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## HF eps Pr(>F[HF])
## trial 0.8432281 0.0007157055
## condition:trial 0.8432281 0.0115972251
## sex:trial 0.8432281 0.8109732471## Anova Table (Type 3 tests)
##
## Response: frustrated_rating
## Effect df MSE F pes p.value
## 1 condition 2, 76 8.55 10.58 *** .22 <.0001
## 2 sex 1, 76 8.55 9.60 ** .11 .003
## 3 trial 2.44, 185.63 0.72 6.52 *** .08 .0008
## 4 condition:trial 4.89, 185.63 0.72 3.02 * .07 .01
## 5 sex:trial 2.44, 185.63 0.72 0.27 .004 .80
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '+' 0.1 ' ' 1
##
## Sphericity correction method: GG## contrast estimate SE df t.ratio p.value
## CC - EC -0.907 0.398 76 -2.281 0.0437
## CC - YC -1.848 0.402 76 -4.600 <.0001
## EC - YC -0.940 0.402 76 -2.341 0.0437
##
## Results are averaged over the levels of: sex, trial
## P value adjustment: holm method for 3 tests## contrast estimate SE df t.ratio p.value
## X10 - X20 0.0101 0.122 228 0.083 1.0000
## X10 - X30 -0.3521 0.122 228 -2.877 0.0136
## X10 - X40 -0.4002 0.122 228 -3.269 0.0062
## X20 - X30 -0.3623 0.122 228 -2.959 0.0136
## X20 - X40 -0.4103 0.122 228 -3.352 0.0056
## X30 - X40 -0.0481 0.122 228 -0.393 1.0000
##
## Results are averaged over the levels of: condition, sex
## P value adjustment: holm method for 6 tests
YC showed highest levels of frustration followed by EC, then CC. Only YC showed an increase in frustration over time. Men in EC reported less frustration.
5.4 Feelings of Helplessness
There were some outliers but excluding them did not change results in a meaningful way, so we kept them.
##
## Univariate Type III Repeated-Measures ANOVA Assuming Sphericity
##
## Sum Sq num Df Error SS den Df F value Pr(>F)
## (Intercept) 2930.50 1 697.44 76 319.3355 < 2.2e-16 ***
## condition 288.10 2 697.44 76 15.6971 1.966e-06 ***
## sex 100.85 1 697.44 76 10.9893 0.001406 **
## trial 1.06 3 162.89 228 0.4934 0.687182
## condition:trial 7.74 6 162.89 228 1.8067 0.098696 .
## sex:trial 0.17 3 162.89 228 0.0786 0.971566
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
##
## Mauchly Tests for Sphericity
##
## Test statistic p-value
## trial 0.35139 2.078e-15
## condition:trial 0.35139 2.078e-15
## sex:trial 0.35139 2.078e-15
##
##
## Greenhouse-Geisser and Huynh-Feldt Corrections
## for Departure from Sphericity
##
## GG eps Pr(>F[GG])
## trial 0.58453 0.5871
## condition:trial 0.58453 0.1397
## sex:trial 0.58453 0.9029
##
## HF eps Pr(>F[HF])
## trial 0.5972275 0.5910637
## condition:trial 0.5972275 0.1382201
## sex:trial 0.5972275 0.9066271## Anova Table (Type 3 tests)
##
## Response: helpless_rating
## Effect df MSE F pes p.value
## 1 condition 2, 76 9.18 15.70 *** .29 <.0001
## 2 sex 1, 76 9.18 10.99 ** .13 .001
## 3 trial 1.75, 133.27 1.22 0.49 .006 .59
## 4 condition:trial 3.51, 133.27 1.22 1.81 .05 .14
## 5 sex:trial 1.75, 133.27 1.22 0.08 .001 .90
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '+' 0.1 ' ' 1
##
## Sphericity correction method: GG## contrast estimate SE df t.ratio p.value
## CC - EC -1.611 0.412 76 -3.908 0.0004
## CC - YC -2.258 0.416 76 -5.423 <.0001
## EC - YC -0.646 0.416 76 -1.553 0.1246
##
## Results are averaged over the levels of: sex, trial
## P value adjustment: holm method for 3 tests
Both stress groups reported sig. greater helplessness compared to the control group, however, they did not differ sig. from each other. Men in EC reported less helplessness.
6 Changes in Affective State
6.1 Depression and Anxiety (STADI)
We excluded two outliers with particularly high pre stress induction STADI scores that affected the results significantly.
##
## Univariate Type III Repeated-Measures ANOVA Assuming Sphericity
##
## Sum Sq num Df Error SS den Df F value Pr(>F)
## (Intercept) 165639 1 3797.2 68 2966.2587 < 2.2e-16 ***
## condition 44 2 3797.2 68 0.3916 0.6774694
## sex 552 1 3797.2 68 9.8863 0.0024687 **
## time 244 1 1171.6 68 14.1641 0.0003516 ***
## condition:time 142 2 1171.6 68 4.1277 0.0203285 *
## sex:time 65 1 1171.6 68 3.7632 0.0565401 .
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1## Anova Table (Type 3 tests)
##
## Response: STADI_S_Global
## Effect df MSE F pes p.value
## 1 condition 2, 68 55.84 0.39 .01 .68
## 2 sex 1, 68 55.84 9.89 ** .13 .002
## 3 time 1, 68 17.23 14.16 *** .17 .0004
## 4 condition:time 2, 68 17.23 4.13 * .11 .02
## 5 sex:time 1, 68 17.23 3.76 + .05 .06
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '+' 0.1 ' ' 1## contrast estimate SE df t.ratio p.value
## CC,pre - EC,pre 1.077 1.73 106 0.623 1.0000
## CC,pre - YC,pre 2.472 1.75 106 1.414 1.0000
## CC,pre - CC,post 0.174 1.17 68 0.148 1.0000
## CC,pre - EC,post -2.840 1.73 106 -1.644 1.0000
## CC,pre - YC,post -1.614 1.75 106 -0.923 1.0000
## EC,pre - YC,pre 1.395 1.77 106 0.790 1.0000
## EC,pre - CC,post -0.903 1.73 106 -0.523 1.0000
## EC,pre - EC,post -3.917 1.20 68 -3.269 0.0238
## EC,pre - YC,post -2.690 1.77 106 -1.523 1.0000
## YC,pre - CC,post -2.298 1.75 106 -1.314 1.0000
## YC,pre - EC,post -5.311 1.77 106 -3.007 0.0428
## YC,pre - YC,post -4.085 1.23 68 -3.329 0.0212
## CC,post - EC,post -3.014 1.73 106 -1.745 1.0000
## CC,post - YC,post -1.788 1.75 106 -1.023 1.0000
## EC,post - YC,post 1.226 1.77 106 0.694 1.0000
##
## Results are averaged over the levels of: sex
## P value adjustment: holm method for 15 tests
Depressive mood and anxiety significantly increased from pre to post stress induction. A significant interaction of group x time indicated that this increase was limited to stress groups, whereas scores did not change in CC. Women in EC displayed greater increase in STADI scores compared to men.
6.2 Positive and Negative Mood (PANAS)
6.2.1 Positive Mood
There were two outliers but excluding them did not change results on positive mood changes, so we kept them.
##
## Univariate Type III Repeated-Measures ANOVA Assuming Sphericity
##
## Sum Sq num Df Error SS den Df F value Pr(>F)
## (Intercept) 115675 1 5896.1 76 1491.0399 < 2.2e-16 ***
## condition 51 2 5896.1 76 0.3278 0.72149
## sex 217 1 5896.1 76 2.7915 0.09888 .
## time 546 1 1014.5 76 40.9117 1.177e-08 ***
## condition:time 8 2 1014.5 76 0.2860 0.75204
## sex:time 1 1 1014.5 76 0.1021 0.75018
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1## Anova Table (Type 3 tests)
##
## Response: PANAS_pos
## Effect df MSE F pes p.value
## 1 condition 2, 76 77.58 0.33 .009 .72
## 2 sex 1, 76 77.58 2.79 + .04 .10
## 3 time 1, 76 13.35 40.91 *** .35 <.0001
## 4 condition:time 2, 76 13.35 0.29 .007 .75
## 5 sex:time 1, 76 13.35 0.10 .001 .75
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '+' 0.1 ' ' 1
Across groups, positive mood decreased from pre to post stress exposure. No significant group differences were observed. There was a trend for sex effects with men in YC showing less decrease in positive mood from pre to post stress induction.
6.2.2 Negative Mood
There were some outliers with respect to negative mood but we did not exclude any participants.
##
## Univariate Type III Repeated-Measures ANOVA Assuming Sphericity
##
## Sum Sq num Df Error SS den Df F value Pr(>F)
## (Intercept) 22680.5 1 756.85 72 2157.6091 < 2.2e-16 ***
## condition 35.9 2 756.85 72 1.7074 0.188588
## sex 97.8 1 756.85 72 9.3050 0.003198 **
## time 23.3 1 311.17 72 5.3974 0.022995 *
## condition:time 44.2 2 311.17 72 5.1097 0.008412 **
## sex:time 7.6 1 311.17 72 1.7562 0.189286
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1## Anova Table (Type 3 tests)
##
## Response: PANAS_neg
## Effect df MSE F pes p.value
## 1 condition 2, 72 10.51 1.71 .05 .19
## 2 sex 1, 72 10.51 9.31 ** .11 .003
## 3 time 1, 72 4.32 5.40 * .07 .02
## 4 condition:time 2, 72 4.32 5.11 ** .12 .008
## 5 sex:time 1, 72 4.32 1.76 .02 .19
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '+' 0.1 ' ' 1## contrast estimate SE df t.ratio p.value
## CC,pre - EC,pre 0.00633 0.756 123 0.008 1.0000
## CC,pre - YC,pre 0.85950 0.771 123 1.115 1.0000
## CC,pre - CC,post 0.72690 0.577 72 1.259 1.0000
## CC,pre - EC,post -1.53987 0.757 123 -2.035 0.4838
## CC,pre - YC,post -0.68636 0.771 123 -0.890 1.0000
## EC,pre - YC,pre 0.85317 0.771 123 1.106 1.0000
## EC,pre - CC,post 0.72057 0.757 123 0.952 1.0000
## EC,pre - EC,post -1.54620 0.579 72 -2.671 0.1216
## EC,pre - YC,post -0.69269 0.772 123 -0.897 1.0000
## YC,pre - CC,post -0.13260 0.771 123 -0.172 1.0000
## YC,pre - EC,post -2.39937 0.772 123 -3.107 0.0352
## YC,pre - YC,post -1.54586 0.601 72 -2.573 0.1457
## CC,post - EC,post -2.26677 0.756 123 -2.999 0.0459
## CC,post - YC,post -1.41326 0.771 123 -1.833 0.6919
## EC,post - YC,post 0.85351 0.771 123 1.107 1.0000
##
## Results are averaged over the levels of: sex
## P value adjustment: holm method for 15 tests## Call:
## bwtrim(formula = PANAS_neg ~ condition * time, id = ID, data = affStates_PANASneg)
##
## value df1 df2 p.value
## condition 0.9831 2 29.2579 0.3862
## time 2.0266 1 41.2255 0.1621
## condition:time 5.8272 2 29.0161 0.0075
There were no sig. group differences but an overall increase in negative mood. Further, we observed a significant group x time interaction with EC showing an increase in negative mood, whereas the increase in YC did not reach significance and CC rather showed a decrease, albeit non-sig. Women in EC and YC reported greater increase in negative mood compared to men.
7 Escape Behaviour
7.1 Activity (moves per minute)
There were some outliers with respect to activity but none of them represented extreme deviations, so we kept them.
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##
## Univariate Type III Repeated-Measures ANOVA Assuming Sphericity
##
## Sum Sq num Df Error SS den Df F value Pr(>F)
## (Intercept) 1648831 1 333858 76 375.3423 < 2.2e-16 ***
## condition 12985 2 333858 76 1.4780 0.234584
## sex 2396 1 333858 76 0.5455 0.462444
## phase 9534 1 79136 76 9.1565 0.003381 **
## condition:phase 1063 2 79136 76 0.5105 0.602223
## sex:phase 626 1 79136 76 0.6016 0.440370
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1## Anova Table (Type 3 tests)
##
## Response: mpm
## Effect df MSE F pes p.value
## 1 condition 2, 76 4392.87 1.48 .04 .23
## 2 sex 1, 76 4392.87 0.55 .007 .46
## 3 phase 1, 76 1041.26 9.16 ** .11 .003
## 4 condition:phase 2, 76 1041.26 0.51 .01 .60
## 5 sex:phase 1, 76 1041.26 0.60 .008 .44
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '+' 0.1 ' ' 1## Call:
## bwtrim(formula = mpm ~ condition * phase, id = ID, data = escapeBehav)
##
## value df1 df2 p.value
## phase 6.4682 1 152.7970 0.0120
## condition 6.0699 2 140.9102 0.0030
## phase:condition 0.7066 2 140.9102 0.4951##
## Univariate Type III Repeated-Measures ANOVA Assuming Sphericity
##
## Sum Sq num Df Error SS den Df F value Pr(>F)
## (Intercept) 8244154 1 1669291 76 375.3423 < 2.2e-16 ***
## condition 64925 2 1669291 76 1.4780 0.234584
## sex 11981 1 1669291 76 0.5455 0.462444
## phase 47671 1 395680 76 9.1565 0.003381 **
## condition:phase 5316 2 395680 76 0.5105 0.602223
## sex:phase 3132 1 395680 76 0.6016 0.440370
## trial 151562 4 1415586 304 8.1371 3.03e-06 ***
## condition:trial 43398 8 1415586 304 1.1650 0.320047
## sex:trial 52621 4 1415586 304 2.8251 0.025122 *
## phase:trial 31718 4 693145 304 3.4777 0.008514 **
## condition:phase:trial 10871 8 693145 304 0.5960 0.781073
## sex:phase:trial 2275 4 693145 304 0.2494 0.909913
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
##
## Mauchly Tests for Sphericity
##
## Test statistic p-value
## trial 0.61935 0.0000459
## condition:trial 0.61935 0.0000459
## sex:trial 0.61935 0.0000459
## phase:trial 0.73366 0.0061037
## condition:phase:trial 0.73366 0.0061037
## sex:phase:trial 0.73366 0.0061037
##
##
## Greenhouse-Geisser and Huynh-Feldt Corrections
## for Departure from Sphericity
##
## GG eps Pr(>F[GG])
## trial 0.82862 1.648e-05 ***
## condition:trial 0.82862 0.32431
## sex:trial 0.82862 0.03423 *
## phase:trial 0.89703 0.01124 *
## condition:phase:trial 0.89703 0.76314
## sex:phase:trial 0.89703 0.89288
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## HF eps Pr(>F[HF])
## trial 0.8709214 1.083877e-05
## condition:trial 0.8709214 3.233215e-01
## sex:trial 0.8709214 3.170030e-02
## phase:trial 0.9469650 9.819693e-03
## condition:phase:trial 0.9469650 7.720967e-01
## sex:phase:trial 0.9469650 9.015552e-01## Anova Table (Type 3 tests)
##
## Response: mpm
## Effect df MSE F pes p.value
## 1 condition 2, 76 21964.36 1.48 .04 .23
## 2 sex 1, 76 21964.36 0.55 .007 .46
## 3 phase 1, 76 5206.31 9.16 ** .11 .003
## 4 condition:phase 2, 76 5206.31 0.51 .01 .60
## 5 sex:phase 1, 76 5206.31 0.60 .008 .44
## 6 trial 3.31, 251.90 5619.66 8.14 *** .10 <.0001
## 7 condition:trial 6.63, 251.90 5619.66 1.16 .03 .32
## 8 sex:trial 3.31, 251.90 5619.66 2.83 * .04 .03
## 9 phase:trial 3.59, 272.70 2541.81 3.48 * .04 .01
## 10 condition:phase:trial 7.18, 272.70 2541.81 0.60 .02 .76
## 11 sex:phase:trial 3.59, 272.70 2541.81 0.25 .003 .89
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '+' 0.1 ' ' 1
##
## Sphericity correction method: GG## contrast estimate SE df t.ratio p.value
## X1 - X2 -8.59 7.69 304 -1.117 1.0000
## X1 - X3 -29.71 7.69 304 -3.863 0.0011
## X1 - X4 -32.93 7.69 304 -4.282 0.0002
## X1 - X5 -33.23 7.69 304 -4.321 0.0002
## X2 - X3 -21.11 7.69 304 -2.745 0.0320
## X2 - X4 -24.34 7.69 304 -3.164 0.0105
## X2 - X5 -24.64 7.69 304 -3.203 0.0105
## X3 - X4 -3.22 7.69 304 -0.419 1.0000
## X3 - X5 -3.52 7.69 304 -0.458 1.0000
## X4 - X5 -0.30 7.69 304 -0.039 1.0000
##
## Results are averaged over the levels of: condition, sex, phase
## P value adjustment: holm method for 10 tests
There were no group differences. Activity was greater in the free exploration phase, without stress exposure compared to the stress phase. Further, activity increased across trials, and differences between the phases were most pronounced at later stages of the experiment.
7.2 Escapes
There were no outliers with respect to number of escapes.
Because residuals were not normally distributed, we employed the Kruskal-Wallis test instead of a one-way ANOVA.
##
## Kruskal-Wallis rank sum test
##
## data: sum_escapes by condition
## Kruskal-Wallis chi-squared = 0.82641, df = 2, p-value = 0.6615There were no significant group differences in escapes.
7.3 Exploration
There were some outliers with respect to exploration but none of them represented extreme deviations, so we kept them.
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##
## Univariate Type III Repeated-Measures ANOVA Assuming Sphericity
##
## Sum Sq num Df Error SS den Df F value Pr(>F)
## (Intercept) 1589304 1 286696 76 421.3072 < 2e-16 ***
## condition 7412 2 286696 76 0.9825 0.37909
## sex 7277 1 286696 76 1.9291 0.16891
## phase 3056 1 49554 76 4.6874 0.03352 *
## condition:phase 979 2 49554 76 0.7507 0.47551
## sex:phase 320 1 49554 76 0.4909 0.48568
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1## Anova Table (Type 3 tests)
##
## Response: exploration
## Effect df MSE F pes p.value
## 1 condition 2, 76 3772.32 0.98 .03 .38
## 2 sex 1, 76 3772.32 1.93 .02 .17
## 3 phase 1, 76 652.02 4.69 * .06 .03
## 4 condition:phase 2, 76 652.02 0.75 .02 .48
## 5 sex:phase 1, 76 652.02 0.49 .006 .49
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '+' 0.1 ' ' 1##
## Univariate Type III Repeated-Measures ANOVA Assuming Sphericity
##
## Sum Sq num Df Error SS den Df F value Pr(>F)
## (Intercept) 7946520 1 1433480 76 421.3072 < 2.2e-16 ***
## condition 37062 2 1433480 76 0.9825 0.37909
## sex 36386 1 1433480 76 1.9291 0.16891
## phase 15282 1 247768 76 4.6874 0.03352 *
## condition:phase 4895 2 247768 76 0.7507 0.47551
## sex:phase 1600 1 247768 76 0.4909 0.48568
## trial 114702 4 1371034 304 6.3582 6.327e-05 ***
## condition:trial 37280 8 1371034 304 1.0333 0.41078
## sex:trial 45495 4 1371034 304 2.5219 0.04117 *
## phase:trial 11781 4 554970 304 1.6133 0.17076
## condition:phase:trial 7944 8 554970 304 0.5439 0.82297
## sex:phase:trial 2427 4 554970 304 0.3324 0.85609
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
##
## Mauchly Tests for Sphericity
##
## Test statistic p-value
## trial 0.67206 0.0005201
## condition:trial 0.67206 0.0005201
## sex:trial 0.67206 0.0005201
## phase:trial 0.76083 0.0159433
## condition:phase:trial 0.76083 0.0159433
## sex:phase:trial 0.76083 0.0159433
##
##
## Greenhouse-Geisser and Huynh-Feldt Corrections
## for Departure from Sphericity
##
## GG eps Pr(>F[GG])
## trial 0.85457 0.0001766 ***
## condition:trial 0.85457 0.4075268
## sex:trial 0.85457 0.0505343 .
## phase:trial 0.90705 0.1767409
## condition:phase:trial 0.90705 0.8067657
## sex:phase:trial 0.90705 0.8384091
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## HF eps Pr(>F[HF])
## trial 0.8996985 0.0001283248
## condition:trial 0.8996985 0.4086527845
## sex:trial 0.8996985 0.0474113001
## phase:trial 0.9581431 0.1734359576
## condition:phase:trial 0.9581431 0.8159063382
## sex:phase:trial 0.9581431 0.8484354479## Anova Table (Type 3 tests)
##
## Response: exploration
## Effect df MSE F pes p.value
## 1 condition 2, 76 18861.58 0.98 .03 .38
## 2 sex 1, 76 18861.58 1.93 .02 .17
## 3 phase 1, 76 3260.11 4.69 * .06 .03
## 4 condition:phase 2, 76 3260.11 0.75 .02 .48
## 5 sex:phase 1, 76 3260.11 0.49 .006 .49
## 6 trial 3.42, 259.79 5277.50 6.36 *** .08 .0002
## 7 condition:trial 6.84, 259.79 5277.50 1.03 .03 .41
## 8 sex:trial 3.42, 259.79 5277.50 2.52 + .03 .05
## 9 phase:trial 3.63, 275.74 2012.64 1.61 .02 .18
## 10 condition:phase:trial 7.26, 275.74 2012.64 0.54 .01 .81
## 11 sex:phase:trial 3.63, 275.74 2012.64 0.33 .004 .84
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '+' 0.1 ' ' 1
##
## Sphericity correction method: GG## contrast estimate SE df t.ratio p.value
## X1 - X2 -6.63383 7.57 304 -0.876 1.0000
## X1 - X3 -24.63596 7.57 304 -3.255 0.0101
## X1 - X4 -28.76343 7.57 304 -3.800 0.0017
## X1 - X5 -28.76005 7.57 304 -3.800 0.0017
## X2 - X3 -18.00213 7.57 304 -2.378 0.0900
## X2 - X4 -22.12960 7.57 304 -2.924 0.0260
## X2 - X5 -22.12623 7.57 304 -2.923 0.0260
## X3 - X4 -4.12747 7.57 304 -0.545 1.0000
## X3 - X5 -4.12409 7.57 304 -0.545 1.0000
## X4 - X5 0.00338 7.57 304 0.000 1.0000
##
## Results are averaged over the levels of: condition, sex, phase
## P value adjustment: holm method for 10 tests
There were no significant group differences. Exploration was greater in the free exploration phase, without stress exposure compared to the stress phase. Also, exploration increased across trials.
7.4 Efficiency
There were some outliers with respect to efficiency but excluding them did not affect the results, so we kept them.
Because residuals were not normally distributed, we employed the Kruskal-Wallis test instead of a one-way ANOVA.
##
## Kruskal-Wallis rank sum test
##
## data: overall_efficiency by condition
## Kruskal-Wallis chi-squared = 2.5018, df = 2, p-value = 0.2863Groups did not differ in behavioural efficiency.
8 Working Memory (Reading Span)
There were some outliers with respect to working memory PCL scores and we excluded them since this affected results significantly.
## Anova Table (Type 3 tests)
##
## Response: pcl
## Effect df MSE F pes p.value
## 1 condition 2, 67 0.01 10.01 *** .23 .0002
## 2 sex 1, 67 0.01 0.08 .001 .78
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '+' 0.1 ' ' 1## contrast estimate SE df t.ratio p.value
## CC - EC 0.1345 0.0303 67 4.443 0.0001
## CC - YC 0.0515 0.0310 67 1.663 0.1011
## EC - YC -0.0830 0.0313 67 -2.655 0.0198
##
## Results are averaged over the levels of: sex
## P value adjustment: holm method for 3 testsThere was a significant main effect of group on working memory performance in the reading span test. EC participants performed signficantly worse than both YC and CC. The latter two groups did not differ.
9 Plots for Figure 1
